In recent years, although a lot of bridges constructed in the past have deteriorated, local self-governing bodies who manage bridges have a limited number of workers who examine bridges. Thus, the use of an unmanned aircraft (so-called drone) that flies via radio control to examine bridges has been proposed. Images photographed using an unmanned aircraft are converted to a panoramic image obtained by stitching a plurality of images, for example, and a bridge is evaluated using the panoramic image.
Moreover, a technique of performing alignment between an image obtained by photographing a wall surface of a tunnel and a plurality of measurement points on the wall surface obtained by measuring the wall surface of the tunnel using a laser scanner using the image and the coordinate values of the plurality of measurement points and the reflection intensity at the measurement points and drawing the image on an exploded plane of the tunnel is proposed.    Patent Document 1: Japanese Laid-open Patent Publication No. 2012-220471    Patent Document 2: Japanese Laid-open Patent Publication No. 2003-115057    Patent Document 3: Japanese Laid-open Patent Publication No. 2003-185589
However, in the examination of bridges using an unmanned aircraft, since a place where the sky is not open such as under a bridge girder is also imaged, a global positioning system (GPS) often does not work and it is difficult to measure a position and an attitude during imaging. Due to this, even when a panoramic image is generated based on photographed images and the generated panoramic image is attached to a three-dimensional model of a bridge, it is difficult to attach the panoramic image with high accuracy due to errors in the position and the attitude of the photographed images.